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/******************************************************************************
  Copyright (c) 1996 Xerox Corporation.  All rights reserved.
  Use and copying of this software and preparation of derivative works based
  upon this software are permitted.  Any distribution of this software or
  derivative works must comply with all applicable United States export
  control laws.  This software is made available AS IS, and Xerox Corporation
  makes no warranty about the software, its performance or its conformity to
  any specification.  Any person obtaining a copy of this software is requested
  to send their name and post office or electronic mail address to:
    Pavel Curtis
    Xerox PARC
    3333 Coyote Hill Rd.
    Palo Alto, CA 94304
    Pavel@Xerox.Com
 *****************************************************************************/

/* md5.c
   MD5 Message Digest Algorithm implementation.
   Ron Frederick

   Derived from RSA Data Security, Inc. MD5 Message-Digest Algorithm
   See below for original license notice.
 */

/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
   rights reserved.

   License to copy and use this software is granted provided that it
   is identified as the "RSA Data Security, Inc. MD5 Message-Digest
   Algorithm" in all material mentioning or referencing this software
   or this function.

   License is also granted to make and use derivative works provided
   that such works are identified as "derived from the RSA Data
   Security, Inc. MD5 Message-Digest Algorithm" in all material
   mentioning or referencing the derived work.  

   RSA Data Security, Inc. makes no representations concerning either
   the merchantability of this software or the suitability of this
   software for any particular purpose. It is provided "as is"
   without express or implied warranty of any kind.  

   These notices must be retained in any copies of any part of this
   documentation and/or software.  
 */

#include "my-string.h"

#include "md5.h"

/*
 * Constants for md5_Transform routine.
 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

static uint8_t PADDING[64] =
{
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/*
 * F, G, H and I are basic MD5 functions.
 */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

/*
 * ROTATE_LEFT rotates x left n bits.
 */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/*
 * FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
 * Rotation is separate from addition to prevent recomputation.
 */
#define FF(a, b, c, d, x, s, ac)			\
    {							\
	(a) += F((b), (c), (d)) + (x) + (uint32_t)(ac);	\
	(a) = ROTATE_LEFT((a), (s));			\
	(a) += (b);					\
    }

#define GG(a, b, c, d, x, s, ac)			\
    {							\
	(a) += G((b), (c), (d)) + (x) + (uint32_t)(ac);	\
	(a) = ROTATE_LEFT((a), (s));			\
	(a) += (b);					\
    }

#define HH(a, b, c, d, x, s, ac)			\
    {							\
	(a) += H((b), (c), (d)) + (x) + (uint32_t)(ac);	\
	(a) = ROTATE_LEFT((a), (s));			\
	(a) += (b);					\
    }

#define II(a, b, c, d, x, s, ac)			\
    {							\
	(a) += I((b), (c), (d)) + (x) + (uint32_t)(ac);	\
	(a) = ROTATE_LEFT((a), (s));			\
	(a) += (b);					\
    }

/*
 * Encodes input (uint32_t) into output (uint8_t). Assumes len is a multiple of 4.
 */
static void
md5_Encode(uint8_t * output, uint32_t * input, int len)
{
    unsigned int i, j;

    for (i = 0, j = 0; j < len; i++, j += 4) {
	output[j] = (uint8_t) (input[i] & 0xff);
	output[j + 1] = (uint8_t) ((input[i] >> 8) & 0xff);
	output[j + 2] = (uint8_t) ((input[i] >> 16) & 0xff);
	output[j + 3] = (uint8_t) ((input[i] >> 24) & 0xff);
    }
}

/*
 * Decodes input (uint8_t) into output (uint32_t). Assumes len is a multiple of 4.
 */
static void
md5_Decode(uint32_t * output, uint8_t * input, int len)
{
    unsigned int i, j;

    for (i = 0, j = 0; j < len; i++, j += 4) {
	output[i] = ((uint32_t) input[j]) |
	    (((uint32_t) input[j + 1]) << 8) |
	    (((uint32_t) input[j + 2]) << 16) |
	    (((uint32_t) input[j + 3]) << 24);
    }
}

/*
 * MD5 basic transformation. Transforms state based on block.
 */
static void
md5_Transform(uint32_t state[4], uint8_t block[64])
{
    uint32_t a = state[0], b = state[1], c = state[2], d = state[3], x[16];

    md5_Decode(x, block, 64);

    /* Round 1 */
    FF(a, b, c, d, x[0], S11, 0xd76aa478);	/* 1 */
    FF(d, a, b, c, x[1], S12, 0xe8c7b756);	/* 2 */
    FF(c, d, a, b, x[2], S13, 0x242070db);	/* 3 */
    FF(b, c, d, a, x[3], S14, 0xc1bdceee);	/* 4 */
    FF(a, b, c, d, x[4], S11, 0xf57c0faf);	/* 5 */
    FF(d, a, b, c, x[5], S12, 0x4787c62a);	/* 6 */
    FF(c, d, a, b, x[6], S13, 0xa8304613);	/* 7 */
    FF(b, c, d, a, x[7], S14, 0xfd469501);	/* 8 */
    FF(a, b, c, d, x[8], S11, 0x698098d8);	/* 9 */
    FF(d, a, b, c, x[9], S12, 0x8b44f7af);	/* 10 */
    FF(c, d, a, b, x[10], S13, 0xffff5bb1);	/* 11 */
    FF(b, c, d, a, x[11], S14, 0x895cd7be);	/* 12 */
    FF(a, b, c, d, x[12], S11, 0x6b901122);	/* 13 */
    FF(d, a, b, c, x[13], S12, 0xfd987193);	/* 14 */
    FF(c, d, a, b, x[14], S13, 0xa679438e);	/* 15 */
    FF(b, c, d, a, x[15], S14, 0x49b40821);	/* 16 */

    /* Round 2 */
    GG(a, b, c, d, x[1], S21, 0xf61e2562);	/* 17 */
    GG(d, a, b, c, x[6], S22, 0xc040b340);	/* 18 */
    GG(c, d, a, b, x[11], S23, 0x265e5a51);	/* 19 */
    GG(b, c, d, a, x[0], S24, 0xe9b6c7aa);	/* 20 */
    GG(a, b, c, d, x[5], S21, 0xd62f105d);	/* 21 */
    GG(d, a, b, c, x[10], S22, 0x2441453);	/* 22 */
    GG(c, d, a, b, x[15], S23, 0xd8a1e681);	/* 23 */
    GG(b, c, d, a, x[4], S24, 0xe7d3fbc8);	/* 24 */
    GG(a, b, c, d, x[9], S21, 0x21e1cde6);	/* 25 */
    GG(d, a, b, c, x[14], S22, 0xc33707d6);	/* 26 */
    GG(c, d, a, b, x[3], S23, 0xf4d50d87);	/* 27 */
    GG(b, c, d, a, x[8], S24, 0x455a14ed);	/* 28 */
    GG(a, b, c, d, x[13], S21, 0xa9e3e905);	/* 29 */
    GG(d, a, b, c, x[2], S22, 0xfcefa3f8);	/* 30 */
    GG(c, d, a, b, x[7], S23, 0x676f02d9);	/* 31 */
    GG(b, c, d, a, x[12], S24, 0x8d2a4c8a);	/* 32 */

    /* Round 3 */
    HH(a, b, c, d, x[5], S31, 0xfffa3942);	/* 33 */
    HH(d, a, b, c, x[8], S32, 0x8771f681);	/* 34 */
    HH(c, d, a, b, x[11], S33, 0x6d9d6122);	/* 35 */
    HH(b, c, d, a, x[14], S34, 0xfde5380c);	/* 36 */
    HH(a, b, c, d, x[1], S31, 0xa4beea44);	/* 37 */
    HH(d, a, b, c, x[4], S32, 0x4bdecfa9);	/* 38 */
    HH(c, d, a, b, x[7], S33, 0xf6bb4b60);	/* 39 */
    HH(b, c, d, a, x[10], S34, 0xbebfbc70);	/* 40 */
    HH(a, b, c, d, x[13], S31, 0x289b7ec6);	/* 41 */
    HH(d, a, b, c, x[0], S32, 0xeaa127fa);	/* 42 */
    HH(c, d, a, b, x[3], S33, 0xd4ef3085);	/* 43 */
    HH(b, c, d, a, x[6], S34, 0x4881d05);	/* 44 */
    HH(a, b, c, d, x[9], S31, 0xd9d4d039);	/* 45 */
    HH(d, a, b, c, x[12], S32, 0xe6db99e5);	/* 46 */
    HH(c, d, a, b, x[15], S33, 0x1fa27cf8);	/* 47 */
    HH(b, c, d, a, x[2], S34, 0xc4ac5665);	/* 48 */

    /* Round 4 */
    II(a, b, c, d, x[0], S41, 0xf4292244);	/* 49 */
    II(d, a, b, c, x[7], S42, 0x432aff97);	/* 50 */
    II(c, d, a, b, x[14], S43, 0xab9423a7);	/* 51 */
    II(b, c, d, a, x[5], S44, 0xfc93a039);	/* 52 */
    II(a, b, c, d, x[12], S41, 0x655b59c3);	/* 53 */
    II(d, a, b, c, x[3], S42, 0x8f0ccc92);	/* 54 */
    II(c, d, a, b, x[10], S43, 0xffeff47d);	/* 55 */
    II(b, c, d, a, x[1], S44, 0x85845dd1);	/* 56 */
    II(a, b, c, d, x[8], S41, 0x6fa87e4f);	/* 57 */
    II(d, a, b, c, x[15], S42, 0xfe2ce6e0);	/* 58 */
    II(c, d, a, b, x[6], S43, 0xa3014314);	/* 59 */
    II(b, c, d, a, x[13], S44, 0x4e0811a1);	/* 60 */
    II(a, b, c, d, x[4], S41, 0xf7537e82);	/* 61 */
    II(d, a, b, c, x[11], S42, 0xbd3af235);	/* 62 */
    II(c, d, a, b, x[2], S43, 0x2ad7d2bb);	/* 63 */
    II(b, c, d, a, x[9], S44, 0xeb86d391);	/* 64 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;

    /* Zeroize sensitive information */
    memset((char *) x, 0, sizeof(x));
}

/*
 * MD5 initialization. Begins an MD5 operation, writing a new context.
 */
void
md5_Init(md5ctx_t * context)
{
    context->count[0] = context->count[1] = 0;

    /* Load magic initialization constants */
    context->state[0] = 0x67452301;
    context->state[1] = 0xefcdab89;
    context->state[2] = 0x98badcfe;
    context->state[3] = 0x10325476;
}

/*
 * MD5 block update operation. Continues an MD5 message-digest operation,
 * processing another message block, and updating the context.
 */
void
md5_Update(md5ctx_t * context, uint8_t * buf, int len)
{
    unsigned int i, index, partLen;

    /* Compute number of bytes mod 64 */
    index = (unsigned int) ((context->count[0] >> 3) & 0x3F);

    /* Update number of bits */
    if ((context->count[0] += ((uint32_t) len << 3)) < ((uint32_t) len << 3))
	context->count[1]++;
    context->count[1] += ((uint32_t) len >> 29);

    partLen = 64 - index;

    /* Transform as many times as possible */
    if (len >= partLen) {
	memcpy((char *) &context->buffer[index], (char *) buf, partLen);
	md5_Transform(context->state, context->buffer);

	for (i = partLen; i + 63 < len; i += 64)
	    md5_Transform(context->state, &buf[i]);

	index = 0;
    } else {
	i = 0;
    }

    /* Buffer remaining input */
    memcpy((char *) &context->buffer[index], (char *) &buf[i], len - i);
}

/*
 * MD5 finalization. Ends an MD5 message-digest operation, writing the
 * the message digest and zeroizing the context.
 */
void
md5_Final(md5ctx_t * context, uint8_t digest[16])
{
    uint8_t bits[8];
    unsigned int index, padLen;

    /* Save number of bits */
    md5_Encode(bits, context->count, 8);

    /* Pad out to 56 mod 64 */
    index = (unsigned int) ((context->count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    md5_Update(context, PADDING, padLen);

    /* Append length (before padding) */
    md5_Update(context, bits, 8);

    /* Store state in digest */
    md5_Encode(digest, context->state, 16);

    /* Zeroize sensitive information */
    memset((char *) context, 0, sizeof(*context));
}

/* 
 * $Log$
 * Revision 1.3  1998/12/14 13:18:04  nop
 * Merge UNSAFE_OPTS (ref fixups); fix Log tag placement to fit CVS whims
 *
 * Revision 1.2  1997/03/03 04:18:51  nop
 * GNU Indent normalization
 *
 * Revision 1.1.1.1  1997/03/03 03:45:00  nop
 * LambdaMOO 1.8.0p5
 *
 * Revision 1.1  1996/02/18  23:19:18  pavel
 * Initial revision
 *
 */